The present invention relates to an antenna for mobile communications. More particularly, it relates to an antenna for mobile communications that has an outer length significantly reduced in comparison to a conventional antenna""s, and assures greatly improved performance.
In recent years, mobile communications equipments have spread far and wide. They became small in size gradually, and much effort has been made into the development of the quality of communication service. There are various mobile communications equipments, and particularly, there are terminals for mobile communications using code-division multiple access (CDMA), time-division multiple access (TDMA), or frequency-division multiple access (FDMA), and iridium terminals using a communications satellite. In these terminals, their antennas are very important parts for keeping good quality of communication service.
Such an antenna should basically have a voltage standing wave ratio (VSWR) of about 1.0, a high gain, a low radio-frequency resistance (RFR), a high emissivity, and a low reflection factor. It is advantageous that the antenna is long in order to increase the gain. When it is too long, its RFR becomes high, and its gain is significantly reduced. Besides, the long antenna gives a user inconvenience.
The antenna used for the conventional terminal for mobile communications is one using a loading coil. Because of the relation of the antenna""s length and gain, there is a limit to the antenna""s length, and if the antenna is mounted within the terminal body, its performance becomes deteriorated to lower the quality of communication service. Hence, the antenna is not embedded in the terminal but protrudes to the outside. Recently, the mobile communications terminal becomes small and light, but its antenna cannot be decreased in size. The protruding antenna may be easily broken or damaged, and when a user carries the terminal in his or her pocket, its antenna that may be caught causes inconvenience to the user for putting it into the pocket or drawing it therefrom.
In addition, since the projecting antenna comes to be near the user""s head during use, the electromagnetic waves that are produced therefrom are deleterious to the human body, and when it contacts the human body, the terminal""s characteristics can be changed to cause noise or cut-off in the middle of telephone communication.
If a cellular phone is installed on an automotive vehicle, an antenna for vehicle cellular phone is provided. However, in the conventional antenna for vehicle cellular phone, its position, direction and length are just controlled in order to enhance the quality of communication service, and this conventional technique could not fundamentally improve the quality of communication service.
The problems of the conventional antenna will be now described referring to FIG. 1.
As depicted in FIG. 1, the conventional antenna is installed on either the front side of an automotive vehicle or the window of its rear side and then connected to a coaxial cable provided to the vehicle""s interior. The conventional antenna is of on-glass type, and this type is a coupling one, and its radio-frequency interference (RFI) is abruptly decreased during real use to deteriorate the quality of communication service and easily cut off the telephone conversation. In addition, this antenna becomes about 53 cm in length when spreading its coil part. When the antenna becomes long like this, the VSWR can be easily controlled but the RFR is increased to lower the quality of communication service. The conventional antenna""s gain is about 0 to 0.4 dBi, and the VSWR is 1.4 to 1.5. Another conventional antenna has low productivity and is of complicated structure.
Accordingly, the present invention is directed to an antenna for mobile communications that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
A first object of the present invention is to provide an antenna of new structure which assures high gain characteristics and improved voltage standing wave ratio (VSWR) with short length, thus enhancing the quality of communication service.
A second object of the present invention is to provide an antenna that is installed within a case of a cellular phone.
A third object of the present invention is to provide an antenna that is used to be mounted on an automotive vehicle or vessel.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, the present invention provides an antenna for mobile communications including first and second bodies of conductor, each having races whose length and diameter are designed in consideration of the antenna""s frequency and gain characteristics; a spacer of a non-conductor interposed between the first and second bodies so as to keep a given space between the respective races of the first and second bodies according to the frequency and gain characteristics; an inner core fixing two bodies to each other with screwed parts respectively inserted into screwed grooves each passing through the races"" bottom, and electrically connecting the first body to the second body; and a coupling part for feeder connection of a transmitting/receiving circuit for a mobile communications terminal.
The inventive antenna can be embedded in a cellular phone terminal to solve inconvenience that occurs by conventional protruding antennas for cellular phone terminal.
An antenna anode region is formed with this inventive antenna installed within the terminal""s case and the coupling part for feeding to one body, and an antenna anode is formed by a shield plate of the cellular phone.
In addition, two antennas of basic structure are installed in the case and one of the antennas serves as a feeder while the other one is an anode region.
In installing the antenna within the terminal, the antenna is disposed outside of the shield plate in a certain direction. When forming the cathode region in the same structure as the anode region""s, two regions can be arranged in the same direction, and the anode region may make a right angle to the cathode region. In addition, each of the antenna coupling part and the antenna connector has a pin hole, and they may be connected to each other by using a pin or via bolt-nut.
The inventive antenna""s gain is higher than conventional ones, thereby enhancing the performance. Since the antenna for a cellular phone terminal is installed in the terminal""s case, this terminal can be variously designed, and obviates any inconvenience that may occur by the projecting antenna.
According to another aspect of the present invention, an antenna includes an antenna base having a through hole into which an antenna cable for communications equipment is inserted, and a plurality of screw holes formed on its bottom to mate with fixing brackets; a connector having a bolt portion joined to the through hole""s upper section, and a connector pin protruding to the bolt portion""s upper and lower parts, a part of the bolt portion being screwed to the through hole of the antenna base, and the antenna cable, inserted into the antenna base, being electrically connected to the connector pin protruding to the lower part; a holder of an insulating material, screwed to the bolt portion of the connector protruding to the upper part of the antenna base, and precisely controlling a minute space between the bolt portion""s upper section and an antenna body for regulating the antenna""s capacitance; a first body having a bolt portion protruding from its lower portion and joined to the holder, the bolt portion having a pin hole into which a connector pin projecting to the connector""s upper part is inserted for electrical connection, and a race of a given depth designed according to the antenna""s transmitting/receiving frequency and gain, the race having screwed grooves on its bottom; an inner core having one end screwed to the screwed grooves, and spaced a given distance away from the inner surface of the first body""s race; a holder of cylindrical shape having a through hole through which the inner core passes, and formed of an insulating material keeping a space of the first and second bodies, designed according to the antenna""s transmitting/receiving frequency and gain; and a second body having a race corresponding to the first body""s, screwed grooves formed on its inner upper section, for receiving the inner core, and a cap formed on its outer upper section.
Each of the fixing brackets includes a fixing disk, corresponding to the bottom of the antenna base, having a plurality of screw holes to which screws are fastened, a cable guide hole formed to receive the antenna cable, and a coupling part formed on one side of the fixing disk to be curved by a given angle (e.g. right angle) and divided into two by an open slit connected to the guide hole in such a manner that the first and second fixing brackets, elastic pieces with compressed elastic force being attached to the coupling part of the first fixing bracket, and the second fixing bracket""s coupling part having a coupling slot into which the elastic pieces of the first fixing bracket are fitted, so that the brackets may be either fixedly inserted into a gap of a car""s interior into which the fixing disk can be fitted, or fixedly installed inside or outside of the car by using screws.
It is to be understood that both the foregoing general description and the following detailed description area exemplary and explanatory and are intended to provide further explanation of the invention as claimed.